Systems and methods for performing phonemic synthesis

Abstract

Systems and methods for performing phonemic synthesis which operate to generate an output data set of acoustic B parameters from a received textual data set wherein the output data set represents patterns of transition from one speech excitation state to another. The textual data set is converted to a plurality of phonetic data sets, at least one phone descriptor is assigned to each of the phonemic data sets, and the output data set is generated by processing the phonetic data sets as a non-linear function of a speech excitation control variable whereby the collective contributions of the phonetic data sets are determined for each pattern of transition from one speech excitation state to another. The speech excitation control variable represents selected portions of a human vocal system.

I claim: 
     
       1. A processing system for generating an output data set for use in phonemic synthesis to produce patterns of transition from one speech excitation state to another, said output data set including a plurality of output data subsets, said processing system comprising: means for receiving a textual data set, said textual data set including at least one textual data subset;   at least one memory storage device operable to store a plurality of processing system instructions; and   at least one processing unit for generating said output data set by retrieving and executing at least one of said processing unit instructions from said memory storage device, said processing unit operable to: transform said received textual data set into a phonetic data set, said phonetic data set including a plurality of phonetic data subsets wherein each of said phonetic data subsets represents a particular speech state, said transformation modelling a number of acoustic parameters affecting the excitation sources of the vocal tract by deriving said parameters as nonlinear functions of a single excitation control variable; and   interpolate said phonetic data set as a function of the single excitation control variable to generate said output data set whereby said phonetic data subsets are combined to determine their collective contributions to each one of said output data subsets.     
     
     
       2. The processing system as set forth in claim 1 further including means for transmitting said output data set to a speech synthesizer in which nearly all excitation of the speech synthesizer is controlled by said single excitation control variable. 
     
     
       3. The processing system as set forth in claim 1, wherein said processing unit is further operable to calculate said physiological variable as a function of selected physical changes as said human vocal system transitions from one speech excitation state to another. 
     
     
       4. The processing system as set forth in claim 3 wherein said physiological variable represents human muscle behavior within said human vocal system, and said processing unit is operable to determine the changes in distance between the vocal cords of said human vocal system for a time period. 
     
     
       5. The processing system as set forth in claim 1, wherein each of said phonetic data subsets represents at least one acoustic feature. 
     
     
       6. The processing system as set forth in claim 5, wherein said acoustic features are selected from the group consisting of: amplitude of fundamental harmonic of voiced sounds;   aggregate amplitude of higher harmonics;   roll-off of higher-frequency of voiced sounds;   amplitude and time envelope of aspiration; and   amplitude and time envelope of fricative sounds; and   at least two of said acoustic features are controlled by said single excitation control variable.   
     
     
       7. The processing system as set forth in claim 1 wherein said single excitation control variable represents the interaction of the plurality of muscles operable to provide control of the human glottis during speech, by varying in proportion to the area of the glottis as defined by the space between the vocal cords, during open-glottis, voiceless sounds, and said processing unit is further operable to derive a time course representing glottal control utilizing a low pass filter. 
     
     
       8. The processing system as set forth in claim 7 wherein said low pass filter models the behavior of the glottal area as the human vocal system transitions from one speech state to another, but the excitation control variable continues beyond the point where measurable glottal area goes nominally to zero. 
     
     
       9. A processing system comprising: an input port for receiving a textual data set including a plurality of textual data subsets; and   at least one processing unit for generating an output data set representing a sequence of speech sounds, said processing unit operable to: calculate an excitation control variable as a function of selected physical changes of a human vocal system as said human vocal system transitions from one speech excitation state to another; and   process said textual data set as a function of said excitation control variable to generate said output data set and model a number of acoustic parameters affecting the excitation sources of the vocal tract by deriving said parameters as nonlinear functions of the excitation control variable, whereby said textual data subsets are converted to a plurality of phonetic data sets which are combined together to determine their collective contributions to each one of said speech sounds.     
     
     
       10. The processing system as set forth in claim 9 further including means for transmitting said output data set to a speech synthesizer in which nearly all excitation of the speech synthesizer is controlled by said excitation control variable. 
     
     
       11. The processing system as set forth in claim 9, wherein said excitation control variable represents human muscle behavior within said human vocal system, and said processing unit is operable to estimate physical muscle changes and glottal area within said human vocal system during transitions from one speech excitation state to another, said excitation control variable varying in proportion to the glottal area during open-glottis voiceless sounds. 
     
     
       12. The processing system as set forth in claim 9, wherein each of said phonetic data sets represents at least one acoustic feature. 
     
     
       13. The processing system as set forth in claim 12, wherein said acoustic features are selected from the group consisting of: amplitude of fundamental harmonic of voiced sounds;   aggregate amplitude of higher harmonics;   roll-off of higher-frequency of voiced sounds;   amplitude and time envelope of aspiration; and   amplitude and time envelope of fricative sounds; and at least two of said acoustic features are controlled by said excitation control variable.     
     
     
       14. The processing system as set forth in claim 9 wherein said excitation control variable represents the interaction of the plurality of muscles operable to provide control of the human glottis during speech, and said processing unit is further operable to derive a time course representing glottal control utilizing an s-shaped filter, but the excitation control variable continues beyond the point where the measurable glottal area goes nominally to zero. 
     
     
       15. The processing system as set forth in claim 14 wherein said s-shaped filter models the behavior of the glottal width as the human vocal system transitions from one speech state to another. 
     
     
       16. A method for generating an output data set of acoustic parameters from a received textual data set, said output data set representative of patterns of transition from one speech excitation state to another, said method comprising the steps of: converting said received textual data set to a phonetic data set, said phonetic data set including a plurality of phonetic data subsets wherein each of said phonetic data subsets represents a particular speech state:   assigning at least one phone descriptor to each of said phonemic data subsets and converting each said assigned phone descriptor to time series;   producing a speech excitation control variable representative of selected portions of a human vocal system;   generating said output data set of acoustic parameters by processing said phonetic data set with a number of acoustic parameters affecting the excitation sources of the vocal tract derived from a non-linear function of said speech excitation variable whereby the collective contributions of the phonetic data subsets are determined for each pattern of transition from one speech excitation state to another.   
     
     
       17. The method as set forth in claim 16 further comprising the step of transmitting said output data set to a speech synthesizer in which nearly all excitation of the speech synthesizer is controlled by said excitation variable. 
     
     
       18. The method as set forth in claim 16 further comprising the step of utilizing said speech excitation variable to determine changes in distance between vocal cords of said human vocal system for a time period. 
     
     
       19. The method as set forth in claim 16 wherein said speech excitation variable represents the interaction of the plurality of muscles operable to provide control of the human glottis during speech, and said method further comprises the step of deriving a time course representing glottal control utilizing a low pass filter. 
     
     
       20. The method as set forth in claim 16 wherein said generating step includes the step of calculating the amplitudes of frication and aspiration.